On the issue of the second movie, it was keeping in line with reality a bit more than the game (which is terrifying that Holly Wood kept in line with reality more than someone else lol)...and even then Nemesis did not die from having its heart impaled from a severe amount of kinetic energy, along with it being unable to regenerate due to an obstruction. Even though the gun was small, it still had far more power than a weapon of its size should have, so I had the reverse issue you did. My belief wasn't destroyed from how small it was, but the damage output for how small it was.

If memory serves, Nemesis in all of its sources was slow and that was a critical weakness. With Gandalfr runes working with it, that double speed boost will be OP lol.

Correction, their weakest stat is E minus which is 5 times the average human. E rank would be 10 times the average though. Pretty sure the stat uses the average human capability not the average maximum, but either way it would be superhuman at D rank and maybe even at E (E minus would likely still be in the realm of possibility for an athlete who focused on a single ability).

He certainly doesn't half-ass romance options, though his battle form is weak.
Could use some experience, like "teaching" Guiche or actually practicing his Chariot skills.
It's a little overwhelming when the difficulty level shot up from noob to insane but you made it work, although I cringed a few times.
My advise is to slow the pacing of the story a bit, and make it more natural. Godspeed.

Okay, I'm dropping this story because of the last chapter, but I have to post this review because of just how terribly executed the last chapter was. Writers often understand that having an MC that destroys all opposition can be a bit boring. To compensate for potentially OP characters, they normally either change the level of many people in the series, elaborating and delving deeper into existing powers, or they offer a reason that the MC isn't as strong as normal. You, however, just inserted a grossly overpowered MC into a world and have him struggle against opponents that he should absolutely demolish. You try to provide reasons for the struggle, mostly centered around the laws of physics, faulty strategies, and what I can only assume to be the desire to hide a majority of their powers. Still, even if your MC was a bumbling idiot, he is still so powerful that Mott (even this stronger version) shouldn't even begin to be able to touch him. In terms of battle prowess, Mott seems to fall short of even some masters, much less an empowered Iskander. The entire situation is akin to throwing Goku into a universe like Naruto and having him struggle again people there, when he should steamroll the entire population.

I feel as though Iskander was severely underpowered during his exchange with Mott. Mott likely wouldn't have been able to really even slow him with his water magic, and the blows would've likely been completely negated by his magic resistance and endurance. Moreover, he could've used Derf to help, and A rank agility would've easily allowed him to get close enough to destroy Mott before he even realized that he moved.